KR101390278B1 - Ball bearing and wind power generator including the same - Google Patents

Abstract

Disclosed are a ball bearing and a wind power generator including the same. The ball bearing according an embodiment of the present invention includes a ball, an inner race, and an outer race. The cross section of the ball has a pair of arc portions which are symmetrical to each other on the basis of a rotation axis of the ball and have a semi-circular shape, and a center portion between the arc portions. The cross section of the inner race consists of two curved surfaces which are symmetrical to each other on the basis of a vertical line passing the center point of the cross section of the ball and being perpendicular to the rotation axis and have the same radius of curvature. The cross section of the inner race has the plane of an orbit of the inner race of which both end portions pass the center point of the first arc portion close to the inner race and are parallel with the rotation axis. The cross section of the outer race consists of two curved surfaces which are symmetrical to each other on the basis of a vertical line passing the center point of the cross section of the ball and being perpendicular to the rotation axis and have the same radius of curvature. The cross section of the outer race has the plane of an orbit of the outer race of which both end portions pass the center point of the second arc portion close to the outer race and are parallel with the rotation axis.

Description

BALL BEARING AND WIND POWER GENERATOR INCLUDING THE SAME}

The present invention relates to a ball bearing and a wind turbine comprising the same.

In recent years, the development of alternative energy to replace petroleum resources is in full swing to solve problems such as global warming and high oil prices. Among these alternatives, wind power generation is attracting attention because there is no emission of pollutants and there is no possibility of harming the environment.

Wind turbines typically include towers, nacelle and rotors.

The nacelle is rotatably supported by the tower. A yaw bearing is interposed between the nacelle and the tower to allow the nacelle to rotate about the tower. The rotor has a form in which the blade is rotatably coupled to the hub, and the pitch angle is adjusted by interposing a pitch bearing between the blade and the hub.

These yaw bearings and pitch bearings are subjected to moment, axial and radial forces in addition to the rotating torque. These bearings can be applied to the ball bearing type of the four-point contact method.

Typical ball bearings include balls, inner rings and outer rings. The ball makes rolling motion while contacting the track surfaces formed on the inner and outer rings at four points. These bearings can elastically deform the ball or raceway surface by the force exerted on the bearings.

When the bearing is elastically deformed, the ball's initial design contact position with respect to the raceway surface changes and, in severe cases, an edge contact occurs where the ball contacts the edge of the raceway surface. If an edge contact occurs, breakage occurs at the edge of the raceway.

Typically, in order to prevent edge contact, a section of the raceway surface over a predetermined distance from the edge at the time of design is set as a contact avoidance region that does not allow contact with the ball. In this case, the ball bearing is designed such that the ball can contact the raceway surface in the contactable area except the contact avoidance area.

However, when the contact avoidance area is set to a large size, the contactable area may be relatively small, which may cause a problem in that the performance of the bearing is degraded.

Japanese Laid-Open Patent Publication No. 2008-281066 (2008.11.20.) Japanese Patent Laid-Open No. 2001-241449 (2001.09.07.)

An embodiment of the present invention is to provide a ball bearing and a wind power generator including the same configured to avoid the edge contact while maintaining or improving the performance of the bearing.

According to an aspect of the present invention, in a ball bearing comprising a ball, an inner ring and an outer ring, the cross section of the ball is a pair of circular arcs symmetrical with respect to the axis of rotation of the ball and each having a semicircular shape, and And a central portion interposed between the arc portions, wherein the cross section of the inner ring consists of two curved surfaces having a center of symmetry and the same radius of curvature with respect to a vertical line passing through the center point of the cross section of the ball and orthogonal to the axis of rotation. And both end portions include an inner ring raceway surface that passes through a center point of the first arc portion close to the inner ring of the arc portions and meets a first straight line parallel to the rotation axis, and a cross section of the outer ring is centered about the vertical line. A second circular arc having two mutually symmetrical surfaces having the same radius of curvature, and having both ends thereof close to the outer ring of the circular arc portions; Going through the center of it, it may be provided with a ball bearing that includes the outer ring raceway surface of intersection with a second straight line parallel with the axis of rotation.

The central portion may have a rectangular shape symmetrical with respect to the vertical line or may have a shape symmetrical with respect to the vertical line and convex in the direction of the rotation axis.

The cross section of the inner ring further includes a pair of inner ring extending surfaces respectively connected to both ends of the inner ring raceway surface and extending in a direction away from a center point of the first arc portion, wherein the cross section of the outer ring is the outer ring raceway surface. And a pair of outer ring extension surfaces respectively connected to both ends of and extending in a direction away from a center point of the second arc portion, wherein the outer ring extension surfaces facing the inner ring extension surfaces and the inner ring extension surfaces, respectively; Can be spaced apart from one another.

According to another aspect of the present invention, a wind turbine including the ball bearing may be provided.

According to an embodiment of the present invention, the cross section of the ball includes a semicircular circular arc portion and a central portion interposed between the circular arc portions, and the raceway surfaces are formed to extend over the entire area of the semicircular circular arc portions, whereby The allowable contact area can be relatively increased while maintaining a constant size of the contact avoidance area, thereby improving the bearing performance and allowing smooth relative rotation of the inner and outer rings.

1 is a view showing a cross section of the ball bearing according to an embodiment of the present invention,
2 is a view showing a cross-section of the ball bearing to be compared of the ball bearing according to an embodiment of the present invention,
3 to 5 are views illustrating a process of providing the ball bearing according to the present embodiment of FIG. 1 by modifying the ball bearing to be compared in FIG. 2.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Referring to the accompanying drawings, the same or corresponding components are denoted by the same reference numerals, do.

1 is a view showing a cross section of the ball bearing according to an embodiment of the present invention. Referring to FIG. 1, the ball bearing 1 according to the present embodiment includes a ball 100, an inner ring 200, and an outer ring 300.

The ball 100 is located between the inner ring 200 and the outer ring 300. When the inner ring 200 and the outer ring 300 rotate relative to each other, the ball 100 rotates and rotates about the rotation axis XR.

The cross section of the ball 100 includes a pair of arc portions 110, 120 and a central portion 130. The pair of arc portions 110 and 120 are mutually symmetrical about the axis of rotation XR of the ball 100 and each has a semicircular shape. Hereinafter, for convenience of description, one of the arc parts 110 and 120 that is close to the inner ring 200 is referred to as the first arc part 110, and one that is close to the outer ring 300 is called the second arc part 120.

 The first arc portion 110 and the second arc portion 120 are interconnected by the central portion 130. The central portion 130 connects the first arc portion 110 and the second arc portion 120 to complete the cross section of the ball 100.

The central portion 130 may have a rectangular shape that is symmetrical with respect to a vertical line X passing through the center point PB of the ball 100 and orthogonal to the rotation axis XR. In this case, the width of the central portion 130 is the same as the diameter of the first arc portion 110 and the second arc portion 120.

Alternatively, although not shown, the central portions may be symmetrical with respect to the vertical line X (see FIG. 1) and convex in the direction of the rotation axis XR (see FIG. 1).

Referring to FIG. 1, the cross section of the inner ring 200 includes an inner ring raceway surface 210 that contacts the ball 100 at two points. The inner ring raceway surface 210 is composed of two curved surfaces 211 and 212. The curved surfaces 211 and 212 are provided so that their centers P11 and P12 are symmetric with respect to the vertical line X, respectively, and their radius of curvature is the same. The curved surfaces 211 and 212 each have a radius of curvature greater than the radius of the first arc portion 110.

Both ends of the inner ring raceway 210 meet the first straight line X1 passing through the center point P1 of the first circular arc part 110 and parallel to the rotation axis XR. At this time, the inner ring raceway 210 may be formed to extend over the entire region of the semi-circular first circular arc portion (110).

When the inner ring raceway surface 210 extends over the entire area of the semicircular first arc portion 110, the inner ring raceway surface allows contact with the ball 100 as compared with the case where the inner ring raceway extends over a portion of the ball. The area A2 may increase relatively. This will be described later.

For reference, in the design process, the inner raceway surface 210 allows the contact avoidance area A1 to contact the ball 100 which does not allow contact with the ball 100 during the operation of the ball bearing 1. It can be distinguished by the contact allowance area A2. In addition, in FIG. 1, the contact avoidance area A1 and the contact allowance area A2 are shown only on the upper side of the vertical line X and the right area of the first straight line X1, but for convenience of drawing, the inner raceway surface 210 ) The entire area and the entire area of the outer raceway surface 310 to be described later.

The cross section of the inner ring 200 further includes a pair of inner ring extending surfaces 230 and 240 respectively connected to both ends of the inner ring raceway 210. The inner ring extension surfaces 230 and 240 extend in a direction away from the center point P1 of the first arc portion 110, respectively. In this case, the inner ring extension surfaces 230 and 240 may be provided in parallel with the rotation axis XR, respectively, but are not limited thereto.

The inner ring extension surfaces 230 and 240 are spaced apart from the outer ring extension surfaces 330 and 340 which will be described later, respectively, to form a space S. The separation space S may be provided to maintain a predetermined width. Spacer space (S) may be arranged, but is not limited to the spacer or ball cage used in conventional ball bearings.

The cross section of the outer ring 300 includes the outer ring raceway surface 310 in contact with the ball 100 at two points. The outer raceway surface 310 is composed of two curved surfaces 311 and 312. The curved surfaces 311 and 312 are provided so that their centers P21 and P22 are symmetric with respect to the vertical line X, respectively, and their radius of curvature is the same. The curved surfaces 311 and 312 each have a radius of curvature greater than the radius of the second arc portion 120.

Both ends of the outer raceway surface 310 meets the second straight line X2 passing through the center point P2 of the second circular arc portion 120 and parallel to the rotation axis XR. In this case, the outer ring raceway surface 310 may extend over the entire area of the second circular arc portion 120.

The outer raceway surface 310 as described above may form a mutual symmetry with the inner raceway surface 210 around the axis of rotation (XR).

The cross section of the outer ring 300 further includes a pair of outer ring extending surfaces 330 and 340 respectively connected to both ends of the outer ring raceway surface 310. The outer ring extension surfaces 330 and 340 extend in a direction away from the center point P2 of the second arc portion 120, respectively. In this case, the outer ring extending surfaces 330 and 340 may be formed in parallel with the rotation axis XR, respectively, but are not limited thereto.

2 is a view showing a cross-section of the ball bearing to be compared of the ball bearing according to an embodiment of the present invention. Hereinafter, a ball bearing and a comparison target ball bearing according to the present embodiment will be described with reference to FIGS. 1 and 2.

First, referring to FIG. 2, the ball bearing 1001 to be compared includes an inner ring 1200 having a ball 1100 having a circular cross section, an inner ring raceway surface 1210 in two-point contact with the ball 1100, and a ball. An outer ring 1300 having an outer ring raceway surface 1310 that is in two-point contact with 1100.

The inner ring raceway surface 1210 includes two symmetrical centers Q11 and Q12 symmetric with each other and having the same radius of curvature about a vertical line Y passing through the center point KB of the ball 1100 and orthogonal to the rotation axis YR. It consists of curved surfaces 1211 and 1212. The outer raceway track surface 1310 includes two curved surfaces 1311 and 1312 having the centers Q21 and Q22 symmetric with respect to the vertical line Y and having the same radius of curvature.

To compare the ball bearing 1001 having the shape as described above and the ball bearing 1 according to the present embodiment shown in FIG. 1, it is assumed that the two bearings are identical in the following points.

Two surfaces 1211 and 1212 for the radius of the ball 1100 of the ball bearing 1001 to be compared, the radius of curvature of the two surfaces 1211 and 1212 of the inner raceway surface 1210, and the center point KB of the ball 1100. Position of the centers of curvature Q11, Q12, radius of curvature of the two surfaces 1311, 1312 of the outer raceway surface 1310, center of the two surfaces 1311, 1312 with respect to the center point KB of the ball 1100. The positions of the Q21 and Q22, the width of the separation space T between the inner ring 1200 and the outer ring 1300, and the length of the contact avoidance area B1 are respectively measured by the ball bearing 1 according to the present embodiment. Radius of the first arc portion 110 and the second arc portion 110, the radius of curvature of the two curved surfaces 211, 212 of the inner ring raceway surface 210, the center P1 of the first arc portion 110 Positions of the centers of curvature P11 and P12 of the two curved surfaces 211 and 212, radius of curvature of the two curved surfaces 311 and 312 of the outer raceway surface 310, and the center P2 of the second circular arc portion 120. The position of the centers of curvature P21 and P22 of the two curved surfaces 311 and 312, the width of the separation space S between the inner ring 200 and the outer ring 300, And the length of the contact avoidance area | region A1 is the same.

Comparing FIG. 1 and FIG. 2 under the above assumption, in the case of the ball bearing 1 according to the present embodiment, the raceway surfaces 210 and 310 extend over the entire area of the arc portions 110 and 120. In the case of the ball bearing 1001 to be compared, it can be seen that the raceways 1210 and 1310 extend over a portion of the ball 1100 having the same radius as the arc portions 110 and 120. In addition, it can be seen that the length of the contact allowable region A2 of the ball bearing 1 according to the present embodiment is larger than the length of the contact allowable region B2 of the ball bearing 1001 to be compared.

Therefore, the ball bearing 1 according to the present embodiment has the same concept of preventing edge contact since the contact avoidance area is the same length as compared with the ball bearing 1001 to be compared, but the contact performance area is relatively large and the bearing performance is large. This is good, which allows smooth relative rotation of the inner and outer rings.

On the other hand, from another viewpoint, the cross section of the ball bearing 1 according to the present embodiment can be provided by modifying the cross section of the ball bearing 1001 to be compared. 3 to 5 are views illustrating a process of providing the ball bearing according to the present embodiment of FIG. 1 by modifying the ball bearing to be compared in FIG. 2.

First, when the left region and the right region of the comparison target ball bearing 1001 of FIG. 2 are moved left and right by a distance corresponding to half of the spaced space T about the rotation axis YR, respectively, FIG. 3. Becomes

In this case, the right region and the left region of the ball 1100 coincide with the first arc portion 110 and the second arc portion 120 of FIG. 1, respectively, and the curved surfaces 1211 and 1212 of the inner raceway surface 1210. Centers Q11 and Q12 and centers Q21 and Q22 of the curved surfaces 1311 and 1312 of the outer ring raceway surface 1310 are centers of the curved surfaces 211 and 212 of the inner raceway surface 210 of FIG. (P11, P12) and the center (P21, P22) of the curved surfaces (311, 312) of the outer ring raceway surface 310.

Thereafter, the left and right regions of the ball 1100 are connected as shown in FIG. 4. In this case, the portion connecting the left and right regions of the ball 1100 coincides with the central portion 130 of FIG. 1.

Subsequently, the inner raceway surface 1210 and the outer raceway surface 1310 of FIG. 4 pass through the centers Q1 and Q2 of the right and left regions of the ball 1100 as shown in FIG. 5, respectively, and are parallel to the rotational axis YR. It extends to the straight lines Y1 and Y2.

Thereafter, the inner ring extensions 1230 and 1240 and the outer ring extensions 1330 and 1340 are respectively moved to both ends of the inner ring raceway surface 1210 and both ends of the outer ring raceway surface 1310 as shown by the arrow of FIG. 5.

Through this process, the ball bearing 1001 of FIG. 2 is matched with the ball bearing 1 according to the present embodiment of FIG. 1.

As can be seen through the above process, the raceway surfaces 210 and 310 of the ball bearing 1 according to the present embodiment of FIG. 1 are the raceway surfaces 1210 of the target ball bearing 1001 of FIG. 2. 1310 may be formed in such a manner that the entire length of the raceways 210 and 310 of the ball bearing 1 according to the present embodiment of FIG. 1 is the raceway of the ball bearing 1001 to be compared of FIG. 2. Larger than faces 1210 and 1310. Therefore, when the two ball bearings 1 and 1001 have contact avoidance areas of the same size, the ball bearing 1 according to the present embodiment may have a larger allowable area than the ball bearing 1001 to be compared.

The ball bearing 1 according to the present embodiment described above can be used in various industrial fields using the ball bearing structure. For example, the ball bearing 1 according to the present embodiment may be provided to a wind turbine.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, many modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

1: ball bearing 100: ball
110: first arc part 120: second arc part
130: center portion 200: inner ring
210: inner ring raceway surface 211, 212: curved surface
230, 240: inner ring extending surface 300: outer ring
310: outer ring raceway surface 311, 312: curved surface
330, 340: outer ring extension surface

Claims (4)

In a ball bearing comprising a ball, an inner ring and an outer ring,
The cross section of the ball,
A pair of circular arcs symmetrical with respect to the axis of rotation of the ball and each having a semicircular shape, and a central portion interposed between the circular arcs;
The cross section of the inner ring,
It consists of two curved surfaces whose centers are mutually symmetric and have the same radius of curvature about a vertical line passing through the center point of the cross section of the ball and orthogonal to the axis of rotation,
Both end portions include an inner ring raceway surface which passes through a center point of the first arc portion close to the inner ring of the arc portions and meets a first straight line parallel to the axis of rotation;
The cross section of the outer ring,
It consists of two curved surfaces whose centers are symmetrical with respect to the vertical line and have the same radius of curvature,
Both end portions include an outer ring raceway surface passing through the center point of the second arc portion close to the outer ring of the arc portions and meets a second straight line parallel to the axis of rotation,
Ball bearing. The method of claim 1,
In the above-
Have a rectangular shape symmetrical with respect to the vertical line or
Symmetrical with respect to the vertical line and having a convex shape in the rotation axis direction,
Ball bearing. The method of claim 1,
The cross section of the inner ring,
A pair of inner ring extending surfaces respectively connected to both ends of the inner ring raceway surface and extending in a direction away from a center point of the first arc portion;
The cross section of the outer ring,
And a pair of outer ring extending surfaces respectively connected to both ends of the outer ring raceway surface and extending in a direction away from a center point of the second circular arc portion.
And the outer ring extending surfaces and the outer ring extending surfaces respectively facing the inner ring extending surfaces are spaced apart from each other. A wind turbine comprising the ball bearing according to any one of claims 1 to 3.

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